133,305 research outputs found
A passive guidance system for a robotic walking assistant using brakes
No full textRobotic walkers are a promising techological direction to improve the mobility of older adults. In this paper, we propose a guidance mechanism based on the differential actions of two brakes located on the rear wheels. The guidance problem can be seen as a complex dynamic path following problem, with limited control authority in the actuators and with important constraints on the user comfort. We cast the problem into an optimisation framework and propose a computationally efficient solution that can be implemented on low cost devices with limited computing power. Simulation results are presented to validate the proposed approach
Visual appearance mapping for optimal vision based servoing
No full textPure appearance based visual maps can be constructed without considering any 3-D spatial information, nevertheless they can be used for robot localization and navigation. This paper proposes a topological framework capable of coordinate multi-agent navigation through an appearance based topological map using only grabbed images as sensory data. A novel image based optimal feature planner is presented, that allows optimal vehicle trajectories. The planner uses a pure visual-based control with a calibrated visual sensor that takes into-account the field-of-view (FOV) constraint of low-cost monocular cameras in order to keep the tracked features in sight while the robot manoeuvres
Visual Servoing on Image Maps
No full textIn this paper we consider the problem of servoing wheeled vehicles in an indoor, initially unknown environment. The proposed approach relies on a hybrid (metric and topological) map built on visual cues. Navigation is planned using topological information to trace a path through viapoints that can be robustly performed by visual servoing control to accurately reach the goal positions. A map of an unknown environment is built as acollection of images taken by an exploratory robot. Images represent nodes in a navigation graph, in which edges represent feasible paths that the robot can execute by visual servoing. Metric and topological information are stored in a hybrid map, which can be shared and cooperatively updated in real time by groups of robots. The merit of the proposed approach is to combine the accuracy of visual servoing methods with a reliable representation of an unknown environment. As a result, the method provides purely visual-based solutions to two of the most relevant problems involved respectively in the field of localization, that is the kidnapped robot problem, and in the field of mapping, that is the closed path detection problem. Experimental results on a laboratory setup are reported, showing the practicality of the proposed approach
A Hybrid-Control Approach to the Parking Problem of a Wheeled Vehicle Using Limited View-Angle Visual Feedback
No full textIn this paper we consider the mobile robot parking problem, i.e. the stabilization of a wheeled vehicle to a given position and orientation, using only visual feedback from low-cost cameras. The practically most relevant problem of keeping the tracked features in sight of the camera while maneuvering to park the vehicle is taken into account. This constraint, often neglected in the literature, combines with the nonholonomic nature of the vehicle kinematics in a challenging controller design problem. We provide an effective solution to such problem by using a combination of previous results on non-smooth control synthesis and recently developed hybrid control techniques. Simulations and experimental results on a laboratory vehicle are reported, showing the practicality of the proposed approach
On the use of Synchronous Ethernet over multiple paths for syntonization of distributed systems
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